He has appeared in many shows, including Criminal Minds (with Nestor Serrano), Alias, The Practice (with Alyson Croft), The West Wing (with Devika Parikh and Tobin Bell), and Days of Our Lives. His voice can be heard in popular cartoon movies, cartoon shows and video games such as Shark Tale, Star Wars: Clone Wars, and The Critic.

As well as his numerous acting credits, Jameson is notable for briefly becoming the fourth member of the English blues-rock band Foghat, and producing several of their albums, including Fool For the City which spawned their greatest single, "Slow Ride". He has since released two solo albums on his own.

Jameson is also a prolific voice actor. He has lent his voice to numerous animated shows and video games through his career.